London (CNN Business)Saudi Aramco shares zoomed higher on Thursday, turning the massive state oil producer into the world's first $2 trillion company and achieving the valuation long sought by Crown Prince Mohammed bin Salman.

The stock gained 10% for a second consecutive day, reaching 38.70 riyals ($10.32) per share before giving up some of its gains.

Saudi Aramco has gained roughly $300 billion in value since its shares debuted on the Riyadh stock exchange on Monday in the biggest initial public offering on record. It's by far the most valuable company in the world, dwarfing runner up Apple, which is worth around $1.2 trillion.

The
vast majority of buyers for the stock are in Saudi Arabia. Samba
Capital, which managed the IPO, said Tuesday that 97% of retail
investors who received shares were from the country. And more than 75%
of shares sold to institutional investors went to Saudi companies, funds
and government institutions.

The
$2 trillion valuation was a priority for the crown prince ever since he
first touted the partial privatization in 2016, but many analysts
considered the figure a stretch despite Aramco's monopoly on oil
production in Saudi Arabia, the world's largest exporter of crude.

Analysts
at Bernstein Research said Thursday that the $2 trillion valuation was
"too much, too soon" given weak expected earnings growth and little
upside for global oil prices. The company looks expensive, they said,
compared to peers such as Exxon(XOM) and Royal Dutch Shell(RDSA).

"Aramco
should trade at a discount rather than premium to international oil
majors," the analysts said. More than 98% of the company is still owned
by the kingdom, they noted, suggesting that investors should be
concerned about corporate governance. Bernstein reckons the company is
worth as little as $1.4 trillion.

"Aramco
could trade in a league of its own for some time, but the stock market
is a weighing machine in the long term and the laws of economic gravity
will eventually apply," said the Bernstein analysts. They recommended
that investors sell Aramco shares now.

The long road to an IPO

International
skepticism over the valuation, combined with low oil prices, the
climate crisis and geopolitical risk, forced Saudi Arabia to scale back
its initial ambitions for the flotation.

The
IPO was supposed to usher in a new era of economic liberalization and
foreign investment in Saudi Arabia. The Saudi government discussed
floating 5% of the company in 2018 in a deal that would raise as much as
$100 billion. It was looking at international markets such as New York
or London, as well as Riyadh.

But
the deal was hampered by concerns about the valuation and potential
legal complications in the United States. It was shelved after the
murder of journalist Jamal Khashoggi in a Saudi consulate in Turkey sent
a chill through business ties with the kingdom.

Yet
the listing was revived earlier this year, and Aramco moved ahead
despite receiving muted interest from international investors. Aramco
ultimately raised $25.6 billion by selling 1.5% of the company at a
valuation of $1.7 trillion.

Gianna
Bern, an energy expert who teaches at the University of Notre Dame's
Mendoza College of Business, said the local offering was able to attract
a "friendly audience" of Saudi nationals. International investors will
watch how the company handles disclosure and regulatory requirements
before considering whether to buy into a potential future international
listing.

"The real test will be a
global offering, in another jurisdiction, such as London or Asia with
more stringent regulatory requirements," said Bern, who is also the
founding principal of energy consultancy Brookshire Advisory and
Research.